The subject of the present invention is a surgical reamer consisting of a rod driven in rotation, equipped with a cutting head having, toward the rear, auxiliary cutting teeth permitting easy withdrawal of the reamer.
Reamers are used in surgery to prepare canals in the bones which are intended to receive implants. These reamers generally have a hollow cutting head which is conical, more precisely, frustoconical. This head is often fixed to the end of a flexible or rigid rod formed by at least one helically wound band of steel. The cutting work in the bone wall has the effect of forming bone chips mixed with a spongy mass. Upon withdrawal of the reamer by the surgeon, this mass has a tendency to cause packing, which slows down the reamer, still continuing to turn, by exerting on the latter a high resistance torque. This resistance torque can even lead to fracturing of part of the reamer. In the case of a flexible rod, this resistance torque can soon cause deformation of the flexible rod. The resistance is particularly great when the surgeon removes the reamer by turning it in the direction counter to the prescribed direction.
In order to facilitate withdrawal of the reamer, it has been proposed to form auxiliary cutting teeth on a frustoconical part to the rear of the head of the reamer. Reamers of this type are described in U.S. Pat. No. 5,122,134, the content of which is incorporated by reference. The auxiliary cutting teeth of these reamers are formed along the continuation of the helices of the principal teeth. These auxiliary cutting teeth permit an easy withdrawal movement of the reamer by virtue of the cutting effect of the teeth situated toward the rear of the reamer. Upon withdrawal of the reamer, the auxiliary teeth cut the bone chips. The spongy mass and the bone chips are able to pass, without causing packing along the flutes formed between the auxiliary teeth.
To achieve the desired favorable effect, the reamer must turn in a defined direction during withdrawal. However, it often happens that the surgeon removes the reamer by turning it in the direction counter to the prescribed direction. Therefore, a need exists for a reamer which avoids the hazards of removal, present in the prior art.